Australian actress Rebel Wilson's record $4.5 million defamation win has been slashed to $600,000 after a successful court appeal by magazine publisher Bauer Media.

In June 2017 a jury found Bauer, the publisher of Woman's Day, Australian Women's Weekly and associated websites, had defamed the Pitch Perfect star in articles that painted her as a "serial liar" and said she had lied about her name, age, and background.

The award included $650,000 in general damages, and $3.9 million in special damages for the movie role opportunities Dixon found Wilson had missed out on due to the defamation.

Bauer Media accepted the jury verdict that it had defamed Wilson, but appealed the size of the payout, saying it was "manifestly excessive". Several media companies in Australia also expressed concern.

On Thursday morning in Melbourne the Victorian Court of Appeal ruled largely in favour of Bauer, ditching Wilson's $3.9 million in special damages entirely and reducing her general damages by $50,000, leaving Wilson with a $600,000 payout.

Wilson was unable to show that the "grapevine effect" had caused the content of the articles to spread to the United States and influence Hollywood decision makers, causing her to miss out on roles, the Court of Appeal judgment says.

"In particular, this court has rejected the finding [by Justice Dixon] that Rebel Wilson lost the opportunity to earn $15 million by being cast in lead or co-lead roles in three Hollywood feature films during the period from mid-2015 to the end of 2016," said Court of Appeal Justice Pamela Tate.

It was this finding that formed the basis for Wilson's initial $3.9 million award in special damages.

Wilson was not in court to hear the decision. She tweeted on Wednesday that she was in Europe filming and wrote "I have already WON the case and this is UNCHALLENGED".

She also said that she planned to donate the money she received in the lawsuit to charity and to support the Australian film industry.

Additionally, I’m away on location in Europe filming right now. The Court of Appeal in Australia will be handing down their decision in the morning re my defamation case against @bauermedia . As I’ve said before, I have already WON the case and this is UNCHALLENGED!

What happens tomorrow is to do with the losers @bauermedia quibbling about how much they now have to pay me. While this case was never about the money for me, I do hope to receive as much as possible to give away to charities and to support the Australian film industry. 🐨